Characteristics of basic silicon solar cells are experimentally researched and theoretically modeled using photons of incandescent lamps as sunlight simulator. It was established that increasing temperature evokes significant acceleration of short-circuit current growth. The reason of it is the shift of simulator spectrum to the higher wavelengths region as compared to the Sun one. This effect leads to a reduction in efficiency decrease for simulated sunlight with the increase of temperature. It should be taken into account in efficiency loss calculation with increase in the operating temperature. It has been shown that the results of theoretical modeling the temperature dependences for the short-circuit current density, open-circuit voltage and photoconversion efficiency are in good agreement with the experimental data obtained using the sunlight simulator. These results could be used to develop methods for investigation of temperature dependences of solar cell characteristics by using various sunlight simulators.